1. Field of the Invention
The present invention pertains to an adjustable aperture apparatus that is used on a bulk material transfer chute that transfers a flow of bulk material from a discharge conveyor to a separate receiving conveyor. In particular, the present invention pertains to an aperture apparatus that is automatically closed when no bulk material is being transferred by the transfer chute from the discharge conveyor to the receiving conveyor. With the apparatus being closed, any residual dust from the bulk material remaining on the discharge conveyor is collected on the closed apparatus and primarily contained in the bulk material transfer chute. When bulk material is again conveyed on the discharge conveyor to the bulk material transfer chute, the conveyed bulk material is deposited on the closed aperture apparatus and the weight of the material causes the apparatus to automatically move to an opened condition, allowing the transfer of the collected dust with the bulk material supplied to the bulk material transfer chute to the receiving conveyor. By collecting the residual dust on the apparatus in the bulk material transfer chute, and then combining the collected dust with the active flow of bulk material through the transfer chute, the aperture apparatus of the invention reduces dust emissions in the area of the transfer chute.
2. Description of the Related Art
The transporting of bulk material, for example coal, from one area to another often involves the transfer of a stream or flow of the material from one conveyor apparatus to another conveyor apparatus. In the transfer of the material from the one conveyor to the other conveyor, it is often necessary that the material be discharged from a discharge end of the one conveyor and transferred onto a receiving end of the other conveyor. To facilitate this transfer of bulk material, large hoppers or transfer chutes have been designed. These transfer chutes receive the flow of material from the discharge conveyor at the top of the chute and deposit or discharge the flow of material onto the other receiving conveyor at the bottom of the chute.
The transfer of bulk material, for example coal, through a transfer chute from the discharge end of one conveyor to the receiving end of a second conveyor inherently produces dust from the transferred bulk material. Most modern bulk material handling systems have been designed to adequately address the problem of dust emissions when the discharge conveyor and the receiving conveyor are operating at their fully loaded states. Basically, the dust created by the transfer of the bulk material from the discharge conveyor, through the transfer chute, to the receiving conveyor is primarily entrapped in the flow of the bulk material. However, when the discharge conveyor and receiving conveyor are operated in an empty state with there being no transfer of the bulk material from the discharge conveyor, through the transfer chute to the receiving conveyor, the dust remaining on the empty discharge conveyor is transferred to the transfer chute. The dust settles through the transfer chute and exits the bottom of the chute where it is emitted into the air surrounding the transfer chute. The airborne dust emissions present a safety and health hazard due to the dust being inhaled by persons working in the area of the transfer chute and the creation of a fire or explosion hazard.